Method of prevention of corrosion in wells



Patented Oct. 21, 1 952 Sims mm mm:

METHOD OF PREIV 'ENTION or CORROSION- N'WELLS 7 Joseph A. Caldwell and Melba L.L:ytle, Houston,

Tex.,

assignors, by mesne' assignments, to

Standard Oil Development Company, Elizabeth, N. 5., a corporation of Delaware N0 Drawing: Application April 3, 1950,

. Serial No. 153,770-

ment which is contacted by the fluid mixture being produced. In many cases it is found that thefluid mixture is acidic in nature and con- 5 Claims. :(cl. 255F855) tains substantial amounts of carbon dioxide, 9.

portion of which dissolves in water or brine presentin the fluids to form carbonic acid. These fluids, including the carbon dioxide, originate in the subsurface formations. In some cases :the corrosion occurs throughout the conduits andattendant equipment through which the fluids are flowed and processed while in other cases the corrosion is limited primarily to rather restricted areas of the conduit and is often par- :ticularly severe in that portion of the conduit adjacent the well head. If corrosion, whether intensive or extensive, is permitted to continue unabated, the conduit and attendant equipment will become sufficiently damaged to require replacement. Not only is the actual costof such replacement high, but other factors may be involved which further increase costs. For example, it may be necessary to kill a high pressure well in order to make the necessary replacements. Furthermore; while replacements andrepairs are being made, there is a loss in revenues due to having the well off production;

Even of more importance than the highcosts incurred as a result of corrosion is the danger that a well will flow wild as a result of the failure of the conduit or equipment due to corrosion. Such a result may be catastrophic. I I It is therefore the main object of" the present invention to provide a method wherebythe corrosivity of corrosive well fluids containing carbon dioxide is substantially eliminated or inhibited in the conduits and attendant equip ment through-which the fluids from subsurface formations are flowed and processedf I v In accordance with the present invention the corrosivity to corrodible ferrous metal surfaces bycorrosive well fluids including moisture and carbon dioxide is eliminated or substantially re-' duced by incorporating in the corrosive fluids a corrosion inhibiting amount of fatty derivatives of polyethylene glycols. The lower molecular weight polyethylene glycols do not yield fattyderivatives which have practical effectiveness in inhibiting corrosion of ferrous metal surfaces by well fluids containing moisture and carbon dioxide. tives of mono-, di-, tri-ethylene glycols are either completelyinefiective or must be used inprohibitive quantities to effect substantial inhibition. The most generally suitable and powerful fatty derivatives of polyethylene glycols are derived from polyethylene glycols. of the type formula (OC2H)x(CH2OH)z in which C designates carbon, H designates hydrogen, 0 desi'g hates oxygen, and X has a 'value of from 3-to' 30. It is preferred to employ a polyethylene glycolin which the value of X in the foregoing formula is in the range of 6 to 15. 'The (OC2H4) group in the foregoing formula will hereinafter be designated by' theterm "ethanoxy group. Fatty derivatives prepared from nonaethylene' glycol, for example, are particularly effective.

Other polyethylene glycols which may be men tioned by way of example include: tetraethylene glycol, pentaethylene glycol, hexaethylene glycol,-

heptaethylene glycol, octaethylene glycol, decaethylene glycol, dodecaethylene glycol, trideca'ethylene glycol, pentadecaethylene glycol,

The fatty material employed to produce thefatty derivatives of polyethylene glycol may be selected from the class of fatty acids and fatty oils. per molecule such as palmitoleic, oleic, ricinoleic, linoleic, linolenic, licanic, arachidonic,

clupanodonic, lauric, my'ristic, arachidic, stearic,

palmitic, etc. and fattyoils from which such acids can be derived may be reacted with thepolyethylene glycols to produce the desired corrosion inhibiting agents. Especially effective agents are obtained by reacting the polyethylenef glycols with such fatty oils as linseed oil,

cottonseed oil, tung oil, oiticica oil, China-wood oil, castor oil, menhaden oil, and the like, or mixtures thereof. Likewise, mixtures of polyethylene glycolsmay be employed. In any event,

the fatty material selected is reacted with the polyethylene glycol selected at a temperature in the range of from 300? to 550 F. for a time in therange of from 1 to 5 hours in the presence of a small amount of an alkalinereacting catalyst such as an alkali hydroxide or carbonate or mixtures thereof. The fatty derivatives of For example, the fatty deriva-L Acids having from '12 to 26 carbon atoms may be made, for example, by reacting ethylene oxide with water, the formation of polyethylene glycols being favored by maintaining the m'olal ratio of ethylene oxide to water in excess of l The degree of polymerization isfurther deter.- a

mined by the reaction conditions maintained.

Polyethylene glycols having molecular ,weights excess of 1500 are commercially available .as well as polyethylene glycols having lower molecular weights. For use in the preparation of the fatty derivatives employed in accordance with the present invention, it is not necessary that the polyethylene glycols be separated into close fractionsof narrow molecular weight limits; on the contrary, fractions including a large number ,of polymers of different molecular weights may be employed- 'When fatty derivatives of the present invenion .are prepared. fromafatty oil, it is preferable that the fatty oil be present in the initial reaction mixture in a Weight ratioof from about lgzltoabout 3:l as comparedto the polyethylene glycol. When the fatty derivative is prepared froma fatty acid, the ,fatty acid should bepresent in the initial reaction mixture in aweight ratio of from about 0.521 to about 2:1 as'compared to the polyethylene-glycol. Only a small amount of the alkaline reaction catalyst need be present, and ordinarily 3 weight per cent or less of; the catalyst based on the Weight-of the reaction mixture is necessary. Forexample, aconcentration of about 1% by weight of sodium hydroxide based upon .the weight of the reactants has been found sufiicient to promote the reac-. tion.- On the other hand, as little as about 5 weight per cent of sodium hydroxide based; on the Weight of the reactants has beenfound sufficientwhen from about 0.5 weight .per cent to about '2 weight per cent of sodium carbonate is utilized as a co-catalyst. Inanother instance 0.05 weight per cent of sodium hydroxide gave good results.

The amount of fattyderivatives of the pres.- ent invention employed to inhibit the corrosion of ferrous metal surfaces by gas-condensate well fluid mixtures including moisture'and carbon dioxide may be varied over a relatively wide-range although it has been found that amounts within the -range of 0.005 per cent to 0.1 per cent by volume of the fluid mixture gives satisfactory results. Ordinarily, however, an amount within the range of 0.005 to 0.01 per cent by volume will give satisfactory inhibition.

Inasmuchas-the fatty derivatives of the presentinvention are soluble in certain solvents, examples of which have been heretofore men? tioned, it may be found convenient to dissolve the fatty derivative in a suitable solvent before introducing it into the corrosive fluid mixture. When it is desired to protect from corrosion the conduit in the borehole, as well as the attendant equipment, the fatty derivative or a solution thereof. may be injected into the borehole adjacent the subsurface formation from which. the corrosive fluid, including carbon dioxideis pro.- duced. Alternatively, the fatty derivativemay be introduced directly into the conduit, A still iuither method of introducing the fatty. derivative into the fluids produced from the subsurface formation involves introducing the fatty derivative or a solution thereof into the annular space between the casing and the tubing. Another method of introducing the fatty derivativeji'nto the subsurface vfluid consists ofinjecting the fatty derivative or a solution thereof into -t l 1e subsurface reservoir through an adjacent Well. femlployed in introducing the fatty derivative into the fluids in the well, the fatty derivative suppresses the corrosivity of the fluids, thereby eliminating. or reducin damage to the conduit,

Irrespective of the particular procedure through'which :the fluids are produced and to attendantequipment through which the fluids are flowed.

In order to determine the effectiveness of the fatty derivatives of polyethylene glycol employed in accordance with the present invention, a derivative was prepared by reacting Chinese tung o l and. no a hyl e e y o T is d vati was prepared in the following manner; 60 grams of Chinese tung oil, 10 grams of nonaethylene glycol, and 0.5 gram of sodium carbonate were ea ed to th at a temp a ure o 5 0 0" for 2 hours. The reaction product thus formed wasadded to a 50:;50 mixture of ,condensa-teand aterob od fro a Well l c d n the-eas-- ensat fie t a y. T x a'th .reao 'on p duc boinga ded to th fl i m xt re; int concentrationof 0.01 percent by volume. c f the foregoing mi tu e wa plac in eachv of two ass. tube and a mi d .st l o up :,sus.-. pend d er in vT luid mixt re nth tub was then saturated with carbon dioxide and the e a ofi- Th oup was immersed in the uidm x uro 31 t m s'per minu of r & d ys- Th ee o h r la s tubes containin 100 cc. of the brine-condensatemixture containing no inhibitor- It will be noted that the .corrosivity. of the aforementioned Well fluid to corrodible ferrous metal was substantially eliminated by the addition of a very small amount of the reaction prod: uct, of tung oil and nonaethylene glycol.

The objects and advantages of the present invention having been fully described and illus-J trated, what We wish to claim as new and useful and to secure by Letters Patent is l. A method for reducing the corrosiveness tocorrodible ferrous metal ofa corrosive well fluid including moisture and carbon dioxide which comprises introducing into said fluid acorrosion inhibiting amount of a reaction product obtained by reacting a fatty material selected from the group consisting of fatty acids having atleast 12 and no more than 26 carbon atoms per-mole.- cule and fatty oils containing fatty acid radicals having no less than l2and no more than 25 carbon atoms with a polyethylene. glycol con; taining at least 3 and no more than 30 'ethanoxy groups in the presence .of an alkaline reacting catalyst selected from. the group consisting ofa kali e al hydrox dea d a k m tal arbon.

for a period of time in the range of 1 to 5 hours at a temperature in the range of 300 to 550 F., the weight ratio of fatty material to polyethylene glycol being in the range of 1:1 to about 3:1.

2. A method in accordance with claim 1 in which the reaction product is added to the corrosive fluid in an amount in the range of 0.005 to 0.1 per cent by volume of the fluid.

3. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting amount in the range of 0.005 to 0.1 per cent by volume of the fluid of a reaction product obtained by reacting tung oil with nonaethylene glycol in the presence of an alkaline reacting catalyst selected from the group consisting of alkali metal hydroxide and alkali metal carbon for a period of time in the range of 1 to 5 hours at a temperature in the range of 300 to 550 F., the weight ratio of tung oil to nonaethylene glycol being in the range of 1:1 to about 3:1.

4. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting amount in the range of 0.005% to 0.1% by volume of the fluid of a fatty derivative obtained by reacting cottonseed oil with nonaethylene glycol in the presence of an alkaline reaction catalyst selected from the group consisting of alkali metal hydroxide and alkali metal carbonate for a period of time in 6 the range of l to 5 hours at a temperature in the range of 300 to 550 F., the weight ratio of cottonseed oil to nonaethylene glycol being in the range of 1: 1 to about 3:1.

5. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous Well fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting amount in the range of 0.005 to 0.1 per cent by volume of the fluid of a fatty derivative obtained by reacting oiticica oil with nonaethylene glycol in the presence of an alkaline reacting catalyst selected from the group consisting of alkali metal hydroxide and alkali metal carbon for a period of time in the range of 1 to 5 hours at a temperature in the 7 range of 300 to 550 F., the Weight ratio of oiticica oil to nonaethylene glycol being in the range of 1:1 to about 3:1.

JOSEPH A. CALDWELL.

MELBA L. LYTLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,249,800 Weber July 22, 1941 2,460,259 Kahler Jan. 25, 1949 2,527,889 Moore Oct. 31, 1950 OTHER REFERENCES Ind. & Eng. Chem., vol. 40, No. 12, p. 2344. Article by Baker et al. 

1. A METHOD FOR REDUCING THE CORROSIVENESS TO CORRODIBLE FERROUS METAL OF A CORROSIVE WELL FLUID INCLUDING MOISTURE AND CARBON DIOXIDE WHICH COMPRISING INTRODUCING INTO SAID FLUID A CORROSION INHIBITING AMOUNT OF A REACTION PRODUCT OBTAINED BY REACTING A FATTY MATERIAL SELECTED FROM THE GROUP CONSISTING OF FATTY ACIDS HAVING AT LEAST 12 AND NO MORE THAN 26 CARBON ATOMS PER MOLECULE AND FATTY OILS CONTAINING FATTY ACID RADICALS HAVING NO LESS THAN 12 AND NO MORE THAN 26 CARBON ATOMS WITH A POLYETHYLENE GLYCOL CONTAINING AT LEAST 3 AND NO MORE THAN 30 ETHANOXY GROUPS IN THE PRESENCE OF AN ALKALINE REACTING CATALYST SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE AND ALKALI METAL CARBON FOR A PERIOD OF TIME IN THE RANGE OF 1 TO 5 HOURS AT A TEMPERATURE IN THE RANGER OF 300* TO 550* F., THE WEIGHT RATIO OF FATTY MATERIAL TO POLYETHYLENE GLYCOL BEING IN THE RANGE OF 1:1 TO ABOUT 3:1. 